1. Field of the Invention
The present invention relates to sorting machines, and, more particularly, to sorting machines for automatically sorting a random stream of articles or products moving along a wide path based upon their color content.
2. Description of the Prior Art
In recent years the cost of labor to manually extract unacceptable comestible products from acceptable products has drastically increased. This increase in the cost of labor has triggered a not insignificant amount of activity in the design and manufacture of sorting machines to accomplish the tasks previously accomplished by manual labor. These machines have made possible the rapid sorting of many comestible products in a number of applications.
The sorting of comestible products according to their degree of ripeness is generally done on the basis of color differences between the ripe and the "green" products. U.S. Pat. No. 3,206,022 refers to one such color sorting machine in which apples are inspected, or viewed, and sorted according to their color characteristics at two selected wavelengths. This and other such color sorters, however, require that the articles being sorted be presented one at a time to a viewing or inspection zone or chamber for the color determination. The capacity of such machines is limited by the need for singulation of the product. Although capacity can be increased by providing a number of such machines side-by-side for parallel operation, the cost is greatly increased. In addition, bichromatic color sorting machines heretofore have been especially sensitive devices not suited to use in rugged environments.
One device intended for sorting a flow of products randomly located across a wide path is described in U.S. Pat. No. 3,872,306, in which ionizing radiation is used to identify dirt clods and stones for separation from potatoes as the potatoes are harvested. Another device for sorting such a flow of products is described in U.S. Pat. No. 3,179,247, in which the separation of rock salt from other matter is accomplished on the basis of differences in translucency. Neither of these devices, however, includes the bichromatic color sorting apparatus required for sorting most comestible products according to degree of ripeness.
Various bichromatic optical devices have been developed for determining the color of articles passing through an inspection chamber or viewing zone. For example, U.S. Pat. No. 3,867,039 relates to an optical system for viewing a large area of a product stream and generating an electrical signal representative of the average color of the articles in the viewed area. This apparatus, however, is not a sorting machine and does not respond to remove unacceptably colored products from the product flow, nor does it individually identify or determine the color of any particular single product article flowing through its viewing area. This apparatus is intended for production process control applications, in which the average color of the product stream is used to control various process parameters.